Some other comments on the dark energy problem.
http://www.nature.com/nature/journal/v466/n7304/full/466321a.html
NATURE | NEWS AND VIEWS
Cosmology forum: Is dark energy really a mystery?
Bianchi, Rovelli, Kolb
Nature 466, 321–322 (15 July 2010)
doi:10.1038/466321a
The Universe is...